Display panel or portion thereof with a graphical user interface



The sole FIGURE is a front view of a display panel or portion thereof with a graphical user interface showing our new design.

The broken lines illustrate the display panel or portion thereof and form no part of the claimed design. The broken lines illustrate portions of the graphical user interface and form no part of the claimed design. 

CLAIM The ornamental design for a display panel or portion thereof with a graphical user interface, as shown and described. 